Lifting dry dock

ABSTRACT

A lifting dry dock for lifting a boat out of the water comprising a subsurface support, a cradle for cradling the boat, and a plurality of legs pivotally connecting the cradle to the subsurface support in a manner which permits movement of the cradle between a lowered position in which the cradle is below the surface of the water a distance sufficient to permit the boat to float thereover and a raised position in which the cradle is clear of the water. A winch is provided for effecting movement of the cradle between its lowered position and its raised position.

United States Patent [19 Knoch Aug. 21, 1973 LIFTING DRY DOCK [76]Inventor: Glen C. Knoch, Lake Ozark, Mo, Primary Examiner Karl Ben 65049Attorney-Irving Powers et al.

[22] Filed: Dec. 2, 1971 ABSTRACT Appl. No.: 204,272

[52] U.S. Cl. 61/65 [51] Int. Cl. B63c 1/02 [58] Field of Search61/64-67; 214/1 [56] References Cited UNITED STATES PATENTS 2,585,6642/1952 May et a] 61/65 X 3,227,292 1/1966 Jacobs 61/67 X 3,220,19611/1965 Schollard 61/65 A lifting dry dock for lifting a boat out of thewater comprising a subsurface support, a cradle for cradling the boat,and a plurality of legs pivotally connecting the cradle to thesubsurface support in a manner which permits movement of the cradlebetween a lowered position in which the cradle is below the surface ofthe water a distance sufficient to permit the boat to float thereoverand a raised position in which the cradle is clear of the water. A winchis provided for effecting movement of the cradle between its loweredposition and its raised position.

5 Claims, 4 Drawing Figures LIFTING DRY DOCK BACKGROUND OF THE INVENTIONThis invention relates to a lifting dry dock for lifting a boat clear ofthe water, and is particularly concerned with a lifting dry dock havinga cradle for cradling the boat, and a pivoted linkage arrangementenabling raising and lowering of the cradle.

It is desirable to remove a boat, such as small pleasure craft, from thewater when out of use to prevent marine life from accumulating on thehull of the boat and to reduce deterioration of the boat. Reference maybe made to such U.S. Pat. Nos. as 2,885,987 and 3,412,702 which are inthe general field of this invention.

SUMMARY OF THE INVENTION Among the several objects of this invention maybe noted the provision of an improved simplified lifting dry dock suchas above-described which cradles a boat as the boat is lifted clear ofthe water; the provision of such a lifting dry dock which accommodatesvarious sizes of boats; the provision of such a lifting dry dock inwhich the boat is moored to the cradle to hold the boat in position forengagement by the cradle; and the provision of such a lifting dock whichis easy to operate and which is of economical construction.

In general, a lifting dry dock of this invention for lifting a boat outof the water comprises a subsurface support, elevator means for liftingthe boat out of the water including a cradle for cradling the boat andpivoted linkage means pivotally mounted on the subsurface support andhaving pivotal connections with the cradle mounting the cradle formovement between a lowered position in which the cradle is below thesurface of the water a distance sufficient to permit the boat to floatthereover and a raised position in which the cradle is clear of thewater. Means are provided for effecting movement of the cradle betweenits lowered position and its raised position. Other objects and featureswill be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of a liftingdry dock of this invention showing its cradle in its raised positionsupporting a boat clear of the water;

FIG. 2 is a side elevation of a lifting dry dock showing in solid linesthe cradle with the boat cradled thereon in its raised position andshowing in phantom the cradle in its lowered position;

FIG. 3 is a plan view showing the cradle associated with a floatingdock; and

FIG. 4 is a vertical section on line 4-4 of FIG. 3 showing the cradle inits raised position.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings. alifting dry clock of this invention, indicated in its entirety at 1, forlifting a boat 14 clear of the water is shown to comprise elevator meansgenerally indicated at 2 which includes a cradle for cradling the boat.The cradle is carried by the lower portion of a floating dock 3, thislowered dock portion being disposed below the surface of the water andconstituting a subsurface support 5 for the cradle. The cradle ismovable by means 'of a pivoted linkage generally indicated at 7 betweena lowered position (as shown in phantom in FIG. 2) in which the cradleis below the surface of the water a distance sufficient to permit theboat to float thereover and a raised position in which the cradle isclear of the water.

More particularly, floating dry dock 3 includes a pair of I-beams, eachbeing indicated at 30, extending transversely of cradle 10, theseI-beams being spaced apart from one another a distance slightly greaterthan the length of the cradle. A pair of cradle support members, eachbeing indicated at 28, are spaced apart from one another a distancecorresponding to the width of the cradle and are secured as by weldingto I-beams 30. A transverse cross brace 31 is welded in place extendingbetween support members 28, this brace member being adjacent theforwardmost l-beam 30 (i.e., the left I- beam as shown in FIG. 1). Thesesupport members 28, I-beams 30 and brace 31 together constitutesubsurface support 5. The floating dock further includes upright members34 which extend from I-beams 30 above the surface of the water forsupporting a pair of side decks, each being indicated at 38, and a frontdeck 39 (see FIG. 3). These decks are arranged to form a boat slip 40 inwhich cradle 10 is mounted on linkage 7 for movement between its loweredposition and its raised position. As shown in FIG. 2, the decks are atsubstantially the same elevation and permit access to boat 14 when thecradle is in its raised position. The upright members 34 of each deckhave cross braces 36 extending diagonally therebetween to rigidize thedock structure. It will be understood that flotation means (e.g., empty55 gallon steel drums, not shown) may be secured to the subsurfacesupport to provide buoyancy for the floating dock.

Cradle 10 is shown to be a horizontal frame having a pair ofspaced-apart side rails 11 which extend the length of the cradle, and aforward member 13 extending transversely between the forward ends of theside rails and being welded thereto. Forward and aft cross members 15aand 15b, respectively (see FIG. 2) extend between the side railsintermediate the ends of the eradle. Each side rail has a forwardshoring member 12a secured thereto adjacent cross member and an aftshoring member 12b secured thereto adjacent cross member 15b. Theseforward and aft shoring members each have a cradle member 9 secured totheir upper ends, the lower end of each of these cradle members.

being secured to the adjacent cross member 15a or 15b. The cradlemembers are engageable with the hull of boat 14 for cradling the boat asthe boat is lifted from the water upon raising of the cradle from itslowered position to its raised position. A post 15 is secured (welded)to the top surface 0 forward member 13, this post being of a heightsufficient to extend above the surface of the water when the cradle isin its lowered position for permitting mooring of one end of boat 14(i.e., its bow) thereto in a manner as will appear. The post is securelyheld in its upright position by braces 16 welded to the sides of thepost and to forward member 13. A vertical elongate slot 18 is providedin the post for purposes as will appear. A vertical column 22 is securedto forward l-beam 30 and extends above the elevation of front deck 39for mounting a winch 24 at a convenient height.

Column 22 is braced in the fore and aft direction by a support brace 35extending between the column and cross brace 31. The winch has a cable26 wound thereon and the cable has a hook 27 on its free end. The winchis provided with a handle 29 for manual operation thereof and has aconventional pawl and ratchet mechanism (not shown) for preventingunwinding of the cable from the winch. Column 22 carries an adjustablestop 33 which is engageable by forward member 13 of the cradle when thecradle is in its raised position to prevent overcentering movement ofthe cradle. It will be understood that a power winch may be used inplace of the manual winch 24.

Linkage means 7 includes four leg members, each of which is indicated at42. These leg members are pivotally connected as indicated at 43 attheir upper ends to the bottom faces of side rails 11 of cradle adjacentforward and aft cross members 15a and 15b, respectively, and arepivotally connected at their lower ends as indicated at 45 to cradlesupport members 28 of subsurface support 7 to enable movement of thecradle between its lowered and raised positions. The leg members onopposite sides of the cradle adjacent the forward cross memberconstitute a forward pair of leg members and are braced laterallyrelative to one another by diagonal braces 32. Similarly, the legmembers pivotally connected to the cradle adjacent the rear cross memberare laterally braced relative to one another by other diagonal braces32. The leg members are substantially the same length and together withthe cradle constitute a parallel linkage arrangement whereby the cradleremains substantially horizontal as it is moved between its lowered andraised positions.

The boat 14 is shown as carrying a fitting or eye-bolt on its bow, thiseye-bolt being adapted to extend through slot 18 in post 15 (see FIGS. 1and 2) when cradle 10 is in its lowered position (as shown in phantom inFIG. 2) for mooring the boat relative to the post when the boat isfloating free above the cradle. Hook 27 on cable 26 is adapted to behooked into eye-bolt 20 so that upon operation of winch 24 to retractthe cable, the boat is pulled against post 15 to hold the boat in properposition for being engaged by cradle members 9 as the cradle is raisedfrom its lowered position. Upon further retraction of the cable, the bowof the boat (or a shoulder (not shown) provided on fitting 20) bearsagainst the post and thereby exerts a forwardly and upwardly actingforce on the post to efiect movement of cradle 10 to its raisedposition. As the cradle is moved upwardly relative to the boat floatingthereabove, eye-bolt 20 moves down in slot 18 and the boat is heldadjacent post 15 by the pulling of the cable on fitting 20, thus theboat is held in position for engagement by the cradle. The cradle may beheld in any position between its lowered position and its raisedposition by engaging the pawl of the above-mentioned pawl and ratchetmechanism of the winch 24 to prevent unwinding of cable 26 from thewinch.

In operation, the lifting dry dock of this invention permits a boat tobe conveniently and quickly lifted clear of the water for storage, andpermits the boat to be readily lowered into the water when desired. Withcradle 10 in its lowered position, and with boat 14 floating adjacentfloating dry dock 5, the boat is maneuvered for entry into slip 40. Thebow of the boat is moved into position'adjacent post 15 which projectsup above the surface of the water and fitting 20 on the bow of the boatis guided into slot 18 of the post. Cable 26 is unwound from winch 24hook 27 on the free end of the cable is hooked in eye-bolt 20. Winch 24is then operated by turning crank 29 to wind up cable 26 thereon. As thecable is retracted, the bow of the boat is pulled against post 15 tothereby exert a force on the post in a generally forward and upwarddirection. Thus, cradle 10 is caused to move on pivoted legs 42 from itslowered position to cradle the boat. Upon further retraction of thecable, the cradle is caused to move to its raised position against stop33. A padlock (not shown) may be inserted in eye-bolt 20 to therebyprevent the eye-bolt from being withdrawn from slot 18 in post 15 foranti-theft purposes.

It will be understood that the length of slot 18 is sufficient toaccommodate boats having fittings 20 installed thereon at variousheights and to accommodate a boat in which its load may vary, wherebythe height of the fitting above the surface of the water may varydepending on the load carried by the boat. It will be further understoodthat cradle members 9 may be adjustable to accommodate boats havingvarious shaped hulls.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

l. A lifting dry dock for lifting a boat out of the water comprising afloating dock having lower portions adapted to lie below the surface ofthe water when said dry dock is floating on the water, these lowerportions constituting a subsurface support, and a deck adapted to extendabove the surface of the water, said lifting dry dock further comprisinga cradle for cradling the boat, pivoted linkage means pivotally mountedon said subsurface support and having pivotal connections with saidcradle mounting said cradle for movement between a lowered position inwhich the cradle is below the surface of the water a distance sufficientto permit the boat to float thereover and a raised position in which thecradle is clear of the water, said deck forming a boat slip in whichsaid cradle is mounted for movement between its lowered position and itsraised position, a winch positioned above and forward of the front endof said cradle, said winch being fixedly mounted relative to saidfloating dry dock at one end, constituting the forward end, of said slipand having a flexible cable for effecting movement of the cradle betweenits lowered position and its raised position upon operation of thewinch.

2. A lifting dry clock as set forth in claim 1 wherein said cradlecomprises a frame having means extending upwardly therefrom at one endthereof constituting its forward end for mooring thereto of one end ofthe boat prior to and during the raising of the cradle, whereby the boatfloating above the cradle is held in position adjacent said mooringmeans to be lifted by the cradle as the cradle is raised from itslowered position to its raised position.

3. A lifting dry clock as set forth in claim 2 wherein said mooringmeans comprises a post secured to and extending upwardly from theforward end of said frame, said post having a vertical slot therein intowhich a fitting carried by the said one end of said boat is adapted tobe inserted, said flexible cable being adapted to be attached to saidfitting as inserted into said slot in said post whereby retraction ofsaid cable by the winch holds the boat against said post and exerts alifting force on said cradle to raise the cradle from its loweredposition to its raised position.

4. A lifting dry dock as set forth in claim 1 wherein said pivotedlinkage means is a parallel linkage means having a plurality of legmembers pivotally connected ity of cradle members adapted to support theboat.

1. A lifting dry dock for lifting a boat out of the water comprising afloating dock having lower portions adapted to lie below the surface ofthe water when said dry dock is floating on the water, these lowerportions constituting a subsurface support, and a deck adapted to extendabove the surface of the water, said lifting dry dock further comprisinga cradle for cradling the boat, pivoted linkage means pivotally mountedon said subsurface support and having pivotal connections with saidcradle mounting said cradle for movement between a lowered position inwhich the cradle is below the surface of the water a distance sufficientto permit the boat to float thereover and a raised position in which thecradle is clear of the water, said deck forming a boat slip in whichsaid cradle is mounted for movement between its lowered position and itsraised position, a winch positioned above and forward of the front endof said cradle, said winch being fixedly mounted relative to saidfloating dry dock at one end, constituting the forward end, of said slipand having a flexible cable for effecting movement of the cradle betweenits lowered position and its raised position upon operation of thewinch.
 2. A lifting dry dock as set forth in claim 1 wherein said cradlecomprises a frame having means extending upwardly therefrom at one endthereof constituting its forward end for mooring thereto of one end ofthe boat prior to and during the raising of the cradle, whereby the boatfloating above the cradle is held in position adjacent said mooringmeans to be lifted by the cradle as the cradle is raised from itslowered position to its raised position.
 3. A lifting dry dock as setforth in claim 2 wherein said mooring means comprises a post secured toand extending upwardly from the forward end of said frame, said posthaving a vertical slot therein into which a fitting carried by the saidone end of said boat is adapted to be inserted, said flexible cablebeing adapted to be attached to said fitting as inserted into said slotin said post whereby retraction of said cable by the winch holds theboat against said post and exerts a lifting force on said cradle toraise the cradle from its lowered position to its raised position.
 4. Alifting dry dock as set forth in claim 1 wherein said pivoted linkagemeans is a parallel linkage means having a plurality of leg memberspivotally connected at their ends to said cradle and to said support,whereby said cradle is maintained in a substantially horizontal positionas it is moved between its lowered and raised positions.
 5. A liftingdry dock as set forth in claim 2 wherein said frame includes a pair ofspaced-apart side rails extending the length of said cradle, a pluralityof cross members extending between the side rails, and a plurality ofcradle members adapted to support the boat.